Room‐Temperature, Low‐Pressure Nanoimprinting Based on Cationic Photopolymerization of Novel Epoxysilicone Monomers

Abstract

The method presented here illustrates a synthetic route that has been developed for the growth of uniaxially aligned ExperimentalThe starting materials for reaction precursors were cobalt nitrite (Co(NO) 3´6 H 2 O, 98 %, Sigma±Aldrich), iron chloride (FeCl 2´4 H 2 O, 99 %, Sigma±Aldrich), oxalic acid (H 2 C 2 O 4 , 99 %, Sigma±Aldrich), cyclohexane (Sigma±Aldrich), n-pentanol (Sigma±Aldrich), and cetyltrimethylammonium bromide (CTAB, Sigma±Aldrich). In a typical synthesis, a quaternary microemulsion consisting of CTAB/water/cyclohexane/n-pentanol was prepared by dissolving CTAB (2.5 g) in a mixture of 75 mL of cyclohexane and 2.5 mL of n-pentanol. The resulting solution was stirred for 20 min. Subsequently, 3.75 mL of an 0.8 M H 2 C 2 O 4 aqueous solution was added into the above solution and the mixture was stirred for an additional 45 min. Finally, 1.25 mL of an aqueous solution containing 0.05 M Co(NO) 3´6 H 2 O and 0.1 M FeCl 2´4 H 2 O was added to the above microemulsion and stirred for 24 h at room temperature. The solid product was recovered by centrifugation and was dried in air at ambient temperature. The solid product was then heated from 100 to 720 C for 2.5 h and annealed at 720 C for another 3 h to obtain the final product. Room-Temperature, Low-Pressure Nanoimprinting Based on Cationic Photopolymerization of Novel Epoxysilicone Monomers** By Xing Cheng, L. Jay Guo,* and Peng-Fei Fu* Nanoimprint lithography (NIL) [1±3] is an emerging lithographic technique that promises high-throughput patterning of nanostructures with great precision. [4,5] The simplicity and high resolution provided by this technique have found numerous applications in electronics, such as in hybrid plastic electronics, [6] organic thin-film transistors and electronics, [7,8] and nanoelectronic devices in Si [9,10] and GaAs; [6,11] in photonics, such as in organic lasers, [12] pixels of high-resolution organic light-emitting diodes, [13] diffractive optical elements, [14] waveguide polarizers, [15] and active [16] and nonlinear optical polymer nanostructures; [17] in magnetic devices, like high-density quantized magnetic discs, [18] and patterned magnetic media; [19] as well as in biological applications, such as manipulating DNA in nanofluidic channels [20±22] and nanoscale protein pat-COMMUNICATIONS

Nanoimprint Lithography: A Processing Technique for Nanofabrication Advancement

“…The resist has the following properties: inherent properties of the resist (with a good substrate adhesion, low shrinkage, low viscosity), coating properties (controllable thickness in the 50∼500 nm, smooth surface, surface roughness is less than 5 nm) and good resistance to etching (at least 1:3 etch selectivity, relative to Si or SiO 2 ) [22][23][24][25].…”

High‐Speed Roll‐to‐Roll Nanoimprint Lithography on Flexible Plastic Substrates

“…For the UV curing, the light intensity depended on the opening ratio of iris and the distance from the source. To determine the curing time and the cured area in relation to the iris opening ratio and distance from UV source, an epoxysilicone resist (10% crosslinker formulation) [20] sandwiched by two PET films was cured by UV irradiation (Fig. 6).…”

“…The material can be crosslinked within a few seconds at a temperature of 120 8C because of the rapid deactivation of the inhibitor. The fast crosslinking ensures high-speed patterning required for R2RNIL For even higher-speed R2RNIL, we used a UV-curable low viscosity liquid epoxysilicone [20] as imprint resist material.…”

Patterning strategies in nanofabrication : from periodic patterns to functional nanostructures

“…Processing cycle time: fast heating systems with negligible resist cooling times by application of heat to the stamp [143] or of a single laser pulse, [144] room temperature systems, [145,146,147] and pressure control, [148,*] demolding implications [149] and incorporation of step-and-repeat systems presence of residual layer [150a] multilevel processing (alignment) [151] contamination control: intermediate polymer stamps (IPS) [152] real-time monitoring systems [153] and feature analysis [150b] Resist visco-elastic properties [154] etch resistance and selectivity thermal stability during thermal imprinting and mechanical stability during demolding [155,156] Mold hardness, durability and surface energy control: anti-adhesive coatings [157,158] and novel anti-adhesive mold materials [147,159,160] mold design rules for optimal filling [161] implications by difference in thermal expansion coefficient between substrate/mold [162] Transfer pattern transfer fidelity of plasma etching [163] * Several efficient strategies to reduce the imprint pressure in nanoimprint lithography are part of soft lithography (see Section 2.3.2).…”

“…Solutions to reduce this adhesion and increase the mold durability are (1) incorporation of internal release agents in resist formulations, (2) application of low-surface energy coatings (in thin film [157] or monolayer [158] of surfactants) to the mold, and (3) fabrication of a mold from materials with intrinsic low surface energy. [147,159,160] The ideal resist formulations for NIL have several characteristic properties for successful pattern transfer, including good deformability at the imprint conditions Siloxane block or graft copolymers [168] also form a potential class of (in this case) Real-time imprint monitoring systems (RIMS) [153] are under development that allow ultimate control over the imprinting process (temperature, pressure, time). The condition for short processing times in IC manufacturing has driven current research activities in thermal NIL to step-and-repeat patterning schemes that have a strong similarity with the stepper system in conventional photolithography.…”